The invention relates to a method for monitoring a functionality of a first and a second component of a motor vehicle. For the monitoring the following relationships exist: for a valid monitoring of the first component a predefined operating condition of the motor vehicle has to be established. For a valid monitoring of the second component the first component has to be functional. The invention also relates to a motor vehicle with a monitoring device for the two components and with a navigation assist device. Components in this context relate in particular to those of emission-lowering devices of the motor vehicle.
In a motor vehicle for example an passenger car it can be provided that the functionality of individual components is regularly monitored by a monitoring device. Thus, an electronic motor control unit of the motor vehicle can be configured to monitor a catalytic converter of the motor vehicle as to whether its oxygen storage capacity is still sufficiently high. For this, a residual oxygen content of an exhaust gas that flows through the catalytic converter can be measured by means of a lambda-probe which is arranged downstream of the catalytic converter. The problem in such a monitoring is that in case of an unrecognized defect of the lambda-probe erroneous measurement values that nevertheless appear plausible, can lead to the fact that a defect of the catalytic converter remains unrecognized by the motor control unit. This can lead to an increased emission of contaminants, which is only recognized when the motor vehicle is examined in a repair shop.
In conjunction with emission-lowering devices of a motor vehicle such as a catalytic converter or an exhaust gas recirculation, the automatic monitoring of the components of these devices by the motor vehicle is mandated by law in some countries. In the European Union such a monitoring device is referred to as European On Board Diagnosis (EOBD). In the US, some states already to date require to equip a motor vehicle with an interface by which a diagnosis device for example in case of a street control can read out actual measuring values of the monitoring device at any time.